Connection apparatus for sections of a rotary furnace



W. L- SHERWOOD Nov. 11,1969

CONNECTION APPARATUS FOR SECTIONS OF A ROTARY FURNACE 2 Sheets-Sheet 1 Filed May 1. 1967 Nov. 11, 1969 w. L. SHERWOOD 3,477,704

CQNNECTION APPARATUS FOR SECTIONS OF A ROTARY FURNACE Filed May 1, 1967 I 2 Sheets-Sheet 2 United States Patent 0 3,477,704 CONNECTION APPARATUS FOR SECTIONS OF A ROTARY FURNACE William Lyon Sherwood, P.O. Box 2161, Vancouver, British Columbia, Canada Filed May 1, 1967, Set. N0. 636,243 Int. Cl. F2711 7/02, 7/26 US. Cl. 26611 7 Claims ABSTRACT OF THE DISCLOSURE by high temperature and the like beingtransmitted direct- 1y across the connection. The embodiment illustrated employs a roller chain coupling which is adapted for conyenient disconnection of one furnacesection and replacement by an alternate one, to facilitate repair of the re fractory lining. There is also a cylindrical screening apparatus adjacent to the coupling adapted for removal of fine-sized materials from the furnace. The screen section is made up in segments, wherein each segment is provided with an enclosing exterior hopper and discharge gate, all held in place within a rigid supporting structure incorporated into the furnace.

The invention relates to elongated rotary furnaces for high-temperature processing, and more particularly, to a connection apparatus forming the junction between two communicating cylindrical sections of a rotary furnace.

Rotary kiln-type furnaces are used in the process industries as reactors for heating and processing of solid or liquid charge materials. The principal processing steps conducted in such furnaces are: (1) heating for solidstate reaction; (2) melting; and (3) refining. Perhaps the majority of rotary kiln furnaces, for example, cement kilns and lime kilns, are used'only for heating and solidstate reaction. There are other processes which include this step and also the steps of melting and refining in which liquid charge materials are present at high temperatures. In those sections of the furnace involvin meltting and refining, refractory erosion is generally more severe requiring more frequent shutdowns for refractory repair and replacement. It is therefore advantageous to provide spare alternate furnace sections for these zones, with a rapid and convenient means of connecting and interchanging them, whereby one furnace section is available and under repair While the other is installed and operating. In this way, long shutdowns are avoided and low-costs are facilitated by achieving near-continuous operation.

In the processing of iron oxide pellets into iron and steel according to my co-pending patent application Ser. No. 398,625 which involves the three stepsabove, just prior to melting a size separation is performed by means of a screen section incorporated into the inner walls of the furnace. This screen section is made up of a plurality of screen deck segments with discharge hoppers, extending in sequence around the furnace circumference. The screen section structure is subject to non-uniform heating with resulting distortion and thermal stresses. It is therefore desirable to isolate these screen sections from the load-carrying part of the furnace structure, and pro- "ice vide a flexible connection between the screen section and at least one end of the furnace to prevent stresses arising from non-uniform heating from being transmitted along to other parts of the furnace shell and structure.

It is an object of this invention to provide a rigid supportingstructure for segmented screen sections of a rotary furnace thereby allowing for thermal distortion of a heated screen area without aifecting adjacent parts of the furnace.

Another object of the invention is to provide a structure for transmission of driving torque from a driving to a driven furnace section across an intermediate screen section.

1 Another object of this invention is to provide for easy, rapid installation of segmented screen and hopper sections Whichmake up a portion of the inner walls of a rotary furnace.

Another object is to provide a means whereby one section of a rotary furnace is driven for rotation by another section, the driving torque for furnace rotation being transmitted from the driving section to the driven section by way of a flexible connection device while at the same time maintaining close communication between the ends of the two sections which are closely coupled together.

It is another object to provide a flexible connection device between sections of a rotary furnace which is easily disconnected for removal of one furnace section and its replacement by another alternate spare furnace section, thereby minimizing delays or shutdowns for furnace relining or repair.

A further object of this invention is to provide a limited degree of free angular, lateral and longitudinal displacement between the two ends of rotary furnace sections which are connected together by a connection device thereby avoiding mechanical forces and stresses being transmitted from one furnace section to another as a result of temperature differences or differences in relative movement of different portions of a rotary furnace on its rollers.

A still further object of this invention is to provide a simple, effective sealing device for a screen section incorporated into the walls of a high-temperature rotary furnace without resorting to the sliding type of mechanical seal.

Other objects, features, and advantages of the invention will become apparent from the description hereinafter, with reference to the accompanying drawings in which: 1 I

FIGURE 1 is an oblique perspective view of two sections of a rotary furnace connected together by means of the apparatus of this invention;

FIGURE 2 is a longitudinal section view at the location of the connection device showing a screening'apparatus as in a characteristic rotary furnace application;

FIGURE 3 is a transverse section view along 1-1 of FIGURE 2 further illustrating the construction of the connection device.

With reference to FIGURE 1, it may be seen the furnace is divided into two cylindrical sections comprising a driving section 1 and a driven section 2. The driving section 1 of the furnace consists of a steel shell lined with refractory which rides on tires 3 supported by rollers 4 mounted on foundations 7. The drive unit for the driving section is not illustrated but is generally similar to that in conventional rotary kiln practice. This driving section 1 is generally the charge end of the furnace unit which is used for heating and solid-state reaction purposes such as reduction of iron ore pellets. The driven section 2 also is equipped with tires 5 and is free to rotate on rollers 6.

In the embodiment illustrated, a screen equipment'is incorporated into the driving section 1 at its discharge end. The screening apparatus is supported within a cagelike structure of rigid members attached to and forming a part of the driving furnace section 1. This support structure comprises a shell-mounted first support ring 9 extending around the entire circumference of the furnace, attached to which are a plurality of longitudinal members 10 which extend the length of the screen itself, and a second drive sprocket support ring 11 which completes the screen support structure.

A plurality of discharge hoppers 16 are mounted inside this cage-structure. There is generally one hopper 16 corresponding to each longitudinal member 10 and the hoppers are supported on the inside by cylindrical flanges which project from the ends of the driving and driven furnace sections and are held in place between these flanges and longitudinal member 10 by set screws or equivalent means of fastening.

The discharge hoppers 16 are provided with discharge gates 17 which open by activation of levers with rollers 18 which contact the cammed surface 19 during the course of rotation. The fine-sized materials passing through the openings in screen deck 27 and into hoppers 10 are thereby discharged into quench tank 21 or other suitable receptacles from whence they may be withdrawn for further processing or recirculation. The coarse-sized materials retained inside the screen deck 27 are passed over darn 26 into a partly fused charge mixture contained by refractory of driven furnace section 2 where they are melted. A burner is provided for melting and the burner inlet 22 is shown as mounted on one of the hoppers 16 through which it projects into the furnace. This burner is supplied by fuel and air controlled by valves 23, 24. The discharge hoppers 16 are generally lined with insulating refractory. This minimizes thermal distortion of the hoppers and also shields longitudinal members 10 and connecting structure from high temperatures within the furnace.

The drive sprocket 12 is mounted around the entire furnace circumference and attached to drive sprocket support ring 11. Driven sprocket 14 is mounted on driven sprocket support ring 15 which in turn is attached and mounted around the circumference of the driven section 2 of the furnace. The connection between the two furnace sections is effected by roller chain 13 made up of pins, support rollers and bushings in a manner similar to a conventional roller chain except that the ends of the pins are designed to accommodate relatively larger longitudinal forces. The driven section 2 of the furnace therefore may be disconnected simply by releasing one of the pins of roller chain 13 and lifting the chain clear of the furnace. The simplicity of this expedient requires a minimum of time and greatly assists in changing furnace sections.

The alternate driven furnace section 29 is also illustrated mounted on auxiliary foundation support brackets 28. For moving the driven sections 2 and 29 from operating to relining stations, a heavy duty transfer cart mounted on tracks may be employed. Alternatively, a separate roller assembly 6 may be provided for each furnace section and the entire roller assembly mounted on slides or tracks as a unit for movement back and forth between operating and relining stations. For illustrative purposes, a refining burner 30 is shown supported by a carriage running on tracks, but it is to be understood for simplicity and clarity there are numerous other details which are not illustrated.

It will be understood that a preferred embodiment of the invention has been described and illustrated and that variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In an elongated, cylindrical rotary furnace, the combination of: a driving furnace section; motor drive means for rotating said driving furnace section; a driven furnace section; a cylindrical screen section forming a portion of the inner furnace walls adjacent the junction between said driving and driven furnace sections; and a flexible coupling for connection and transmission of torque for rotation from said driving furnace section to said driven furnace section.

2. A rotary furnace apparatus according to claim 1 wherein said flexible coupling comprises two adjacent circnmferential sprockets connected by a common roller chain, one of said sprockets mounted on said driving furnace section and the other mounted on said driven furnace section, thereby allowing a substantially fixed and limited amount of angular, lateral and longitudinal displacement between the adjacent ends of said driving furnace section and driven furnace section during furnace rotation.

3. A rotary furnace apparatus according to claim 1 wherein said screen section comprises a plurality of segmented screen decks extending in sequence around the inner circumference of the furnace, said screen decks having enclosing exterior hoppers for receiving with discharge openings for discharging fine-sized materials passing through said screen decks.

'4. A rotary furnace apparatus according to claim 1 wherein said screen section comprises a plurality of segmented screen decks each having an enclosing exterior hopper to form an integral unit, the sides of said units being butted together in sequence around the inner circumference of the furnace to make up a cylindrical screen wall section, with one end of said units being supported and in contact with an inner support flange attached to said drivin furnace section and the other end with an inner support flange attached to said driven furnace section, and having a discharge gate in each of said hoppers which is opened only periodically for discharge of finesized materials, whereby the screen section assembly is adapted to effect a substantially gas-tight seal between the interior and exterior of the furnace at the transition between said driving and driven furnace sections.

5. In an elongated, cylindrical rotary furnace, the combination of: a driving furnace section; motor drive means for rotating said driving furnace section; a driven furnace section; a flexible coupling for connection and transmission of torque for rotation from said driving furnace section to said driven furnace section; a cylindrical screen section forming a portion of the inner furnace walls which comprises a plurality of segmented screen decks, each having an enclosing exterior hopper to form an integral unit, the sides of said units being butted together in sequence around the inner circumference of the furnace to make up a cylindrical screen wall section, with one end of said units being supported and in contact with an inner support flange attached to said driving furnace section and the other end with an inner support flange attached to said driven furnace section, and having a discharge gate in each of said hoppers which is opened periodically for discharge of fine-sized materials; a rigid exterior cage-structure adapted to hold said integral screen and hopper units in place against said support flanges comprising a plurality of longitudinal members which are connected in fixed relation to the furnace shell at one end and terminate at their opposite end with a circumferential support for said flexible coupling, whereby said cage-structure and screen section assembly is adapted to effect a substantially gas-tight seal between the interior and exterior of the furnace at the transition between said driving and driven furnace sections.

6. A rotary furnace apparatus according to claim 5 wherein said hoppers are held in position between said longitudinal members and inner support flanges by means of adjustable fasteners adapted for convenient removal of each said integral hopper and screen units independently of the other units.

7. A rotary furnace apparatus according to claim 5 wherein said flexible coupling comprises two adjacent circumferential sprockets connected by a common roller chain, one sprocket mounted on one circumferential-support on said driving furnace section and the other on a second circumferential support on said driven furnace section.

(References on following page) 5 6 References Cited 1. SPENCER OVERI-IOLSER, Primary Examiner UNITED STATES PATENTS I. S. BROWN, Assistant Examiner 1,188,566 6/1916 Singer 263-33 3,295,930 1/1967 Swanson et a1. 26332 US. Cl. X.R.

3,386,718 6/1968 Abbott 263-33 26333;266-1-8 

